The use of telematics systems on assets to track the assets is common among companies that have a fleet of vehicles, for example, tractors and trailers. Typically, telematics systems include components such as communication units, processors, devices for inputs and outputs, and various sensors. Many of these telematics systems involve components that are installed on both the tractor and the trailer. It would be desirable to establish communications between the telematics systems on a tractor with the telematics system on a trailer to exchange various information. For example, such communications would be useful in determining which tractor is attached to which trailer. Frequently, wireless communications units are installed on the tractor and trailer as the means of communication between the tractor and the trailer.
Basic data transfer systems for transmitting information between a pulling vehicle and a trailer are known. One such system is disclosed in U.S. Pat. No. 5,854,517. This system involves establishing a wired communication link between a tractor and a trailer by utilizing certain existing dormant tractor and trailer circuitry. In one embodiment of this system, a tractor communications device has a communications port connected to the turn signal circuit and a trailer communications device has a communications port connected to the same turn signal circuit. The two communications devices permit communications between the tractor and the trailer over the turn signal circuit as long as the turn signal circuit is inactive. Conversely, if the turn signal circuit becomes active, it would inhibit the communications between the tractor and the trailer.
Accordingly, this type of prior art system can only allow communications between a tractor and a trailer when the particular circuitry is not in use and, therefore, communications are cut off when the particular circuitry is in use. Moreover, this system consumes valuable resources of the wired circuitry to support the communications between the tractor and the trailer.
Other types of wired communications devices are disclosed in U.S. Pat. Nos. 5,142,278, 5,025,253 and 4,897,642. These patents disclose systems that would transfer data between the tractor and the trailer using existing power lines connected between the tractor and the trailer. However, the systems disclose in these patents have three major problems. First, these systems require additional components to be installed on both the tractor and the trailer, thereby increasing the costs for operation, making it uneconomical to utilize these systems. Second, because most telematics systems installed on tractors and trailers already have wireless communication capabilities, it would be redundant to add a second means of communication between the tractor and the trailer. Third, wireless transfer of data, for example, by RF, is much faster than wired transfer of data through a power line connecting the tractor and the trailer. Thus, it would be much more efficient to use the wireless communication devices that are already available on telematics systems installed on tractors and trailers, instead of using power lines to transfer data.
In order to avoid some of the problems arise from wired communications systems using existing circuitries, a wireless data transfer system for a tractor and a trailer is disclosed in U.S. Pat. No. 7,142,098. The U.S. Pat. No. 7,142,098 patent discloses a wireless data transfer system having a first and a second wireless communications units carried across a hitch space between the rear of a tractor cab and the front of the trailer. The two wireless communications units transmit data from sensors in the trailer across the hitch space to a notification device in the tractor. This communication system eliminates the use of connection wires and hence avoid the problems of wired communication systems.
However, a problem that can arise from the prior art wireless communication system is the incorrect binding of wireless communications units. If a number of tractors and trailers are in close proximity, for example, in a tractor-trailer parking lot, the wireless communications units may communicate with the incorrect tractor or trailer, resulting in errors in communication. Thus, there is a need for a wireless tractor-trailer binding system to ensure that the telematics system on the tractor would be communicating to the telematics system on the correct trailer, and vice versa. At the same time, the binding method needs to be sufficiently simple to prevent excess consumption of resources. The present invention provides a method of fast and simplified tractor-trailer wireless binding that can minimize false tractor and trailer wireless links.
The present invention uses components that are already installed on tractors and trailers, eliminating the need to install additional components. In addition, the present invention does not transfer data between power lines connecting the tractor and the trailer, thereby eliminating the redundancy of multiple means of communication. At the same time, the present invention provides fast data transfer through the wireless communications devices already installed in the telematics systems. And because the present invention utilizes power pulses, it is also capable of detecting loss of ABS/EBS power, allowing the telematics system to generate alarms promptly and accurately.